An air-cushioned landing craft, also called an LCAC (landing craft, air cushioned) is a modern variation on the amphibious landing boat. These craft are based on small- to mid-sized multi-purpose hovercraft, also known as "over the beach" ("OTB") craft. This allows troops and material to access more than 70 percent of the world's coastline, while only approximately 15 percent of that coastline is available to conventional boat-type landing craft. Typical barriers to conventional landing craft are soft sandy beaches, marshes, swampland, and loose surfaces. Air cushion technology has vastly increased the landing capability of the craft, providing greater speed and flexibility over traditional landing craft.